So the gasket was leaking and Im sure the ATF was pretty old. Yesterday I drained the pan, replaced the filter and renewed the gasket. I filled it with DEx/ Mercon ATF. This moring when i started it there is a new sound to the transmission. It has a low dull knocking sound. Is that ok? Does the Dex/Mercon have different propertied than original DEx II that is says to use. Or should i switch to someting else? I do not want to ruin my tranny. The van is a 1994 s/c alltrac.